[new feature] Notify: add new prop zIndex

fix #1498

packages/notify/index.less

@@ -3,7 +3,6 @@
 .van-notify {
   position: fixed;
   top: 0;
-  z-index: 110;
   width: 100%;
   padding: @notify-padding;
   font-size: @notify-font-size;

packages/notify/index.ts

@@ -18,6 +18,10 @@ VantComponent({
     duration: {
       type: Number,
       value: 3000
+    },
+    zIndex: {
+      type: Number,
+      value: 110
     }
   },
 

packages/notify/index.wxml

@@ -2,7 +2,7 @@
   name="slide-down"
   show="{{ show }}"
   custom-class="van-notify"
-  custom-style="background-color:{{ backgroundColor }}; color: {{ color }};"
+  custom-style="background-color:{{ backgroundColor }}; color: {{ color }}; z-index: {{ zIndex }};"
 >
   <view wx:if="{{ safeAreaInsetTop }}" class="van-notify__safe-top" style="padding-top: {{ statusBarHeight }}px"></view>
   {{ text }}

packages/notify/notify.ts

@@ -1,6 +1,6 @@
 import { isObj } from '../common/utils';
 
-type NotifyOptions = {
+interface NotifyOptions {
   text: string;
   color?: string;
   backgroundColor?: string;
@@ -8,7 +8,8 @@ type NotifyOptions = {
   selector?: string;
   context?: any;
   safeAreaInsetTop?: boolean;
-};
+  zIndex?: number;
+}
 
 const defaultOptions = {
   selector: '#van-notify',
@@ -16,10 +17,10 @@ const defaultOptions = {
 };
 
 function parseOptions(text: NotifyOptions | string): NotifyOptions {
-  return isObj(text) ? text as NotifyOptions : { text } as NotifyOptions;
+  return isObj(text) ? (text as NotifyOptions) : ({ text } as NotifyOptions);
 }
 
-function getContext() {
+function getContext(): Page.PageInstance {
   const pages = getCurrentPages();
   return pages[pages.length - 1];
 }